Interpretive Summary: Over the last 20 years, four National Beef Quality Audits (NBQA) have been conducted. Continuing to follow the recommendation to survey the beef quality attributes of the US fed beef supply every 4 to 5 years, the 2011 NBQA was conducted to assess the current status of the quality and consistency of fed steers and heifers. With the recent implementation of instrument grading, the opportunity to measure quality attributes and trends over the course of a year with a very large dataset has been feasible for the first time as part of the NBQA. One week of instrument grading data were collected every other month (n = 2,427,074 carcasses) over a 13-month period from four beef processing corporations, encompassing 17 federally inspected beef processing facilities. Shifts in the mean of certain quality grade and yield grade traits occurred on a month-to-month basis. This dataset provided the opportunity to follow seasonal trends in a whole array of value-determining factors for the beef industry.

Technical Abstract:
The instrument grading assessments for the 2011 National Beef Quality Audit evaluated seasonal trends of beef carcass quality and yield attributes over the course of the year. One week of instrument grading data, HCW, gender, USDA quality grade (QG), and yield grade (YG) factors, were collected every other month (n= 2,427,074 carcasses) over a 13-mo period (November 2010 through November 2011) from 4 beef processing corporations, encompassing 17 federally inspected beef processing facilities, to create a “snapshot” of carcass quality and yield attributes and trends from carcasses representing approximately 8.5% of the U.S. fed steer and heifer population. Mean yield traits were YG (2.86),HCW (371.3 kg), fat thickness (1.19 cm.), and LM area (88.39 cm2). The YG distribution was YG 1, 15.7%; YG 2, 41.0%; YG 3, 33.8%; YG 4,8.5%; and YG 5, 0.9%. Distribution of HCW was <272.2 kg, 1.6%; 272.2 to 453.6 kg, 95.1%; and =453.6 kg, 3.3%. Monthly HCW means were November 2010, 381.3 kg; January 2011, 375.9 kg; March 2011, 366.2 kg; May 2011, 357.9 kg; July 2011, 372.54 kg; September 2011, 376.1 kg; and November 2011, 373.5 kg. The mean fat thickness foreach month was November 2010, 1.30 cm; January 2011,1.22 cm; March 2011, 1.17 cm; May 2011, 1.12 cm; July 2011, 1.19 cm; September 2011, 1.22 cm; and November 2011, 1.22 cm. The overall average marbling score was Small**49. The USDA QG distribution was Prime, 2.7%; Top Choice, 22.9%; Commodity Choice, 38.6%; and select, 31.5%. Interestingly, from November to May, seasonal decreases (P < 0.001) in HCW and fat thicknesses were accompanied by increases (P < 0.001) in marbling. These data present the opportunity to further investigate the entire array of factors that determine the value of beef. Data sets using the online collection of electronic data will likely be more commonly used when evaluating the U.S. fed steer and heifer population in future studies.